Oats (Avena sativa), and especially colloidal oatmeal suspensions have been used historically as adjuncts to the treatment of atopic dermatitis. It is desirable to extract the active ingredients from the oat in order to facilitate the use of the grain in medicinal and cosmetic applications.
Oat derivatives such as colloidal oatmeal, hydrolysed oat protein, oat starch, and β glucan have been used in the cosmetics and pharmaceutical industries as a skin protectant which provides a smooth feel after use. Specifically, the carbohydrates and protein in the oat derivatives have been known to function as a protectant to aid in enhancing the skin's barrier properties and thereby soothe the skin. Oat β glucans and lipids have also been known to function as emollients to lubricate and soothe the skin. For example, colloidal oatmeal has been used for bar soaps, bath powders, lotions, and poultices to treat skin that has been damaged, irritated, or distressed by a wide variety of causes. However, some oat derivatives, for example, colloidal oatmeal, are not fully soluble in aqueous solutions and leave undesirable residues on the skin and other surfaces.
U.S. Pat. No. 5,219,340 describes a cloth applicator designed to retain colloidal oatmeal insoluble fractions.
Furthermore, hydrolysed oat protein undergoes processes such as hydrogenation, which may alter or adversely effect their properties. In particular, acid hydrolysed oat protein is known to have a strong odour which may adversely affect some consumer's acceptance of the product.
Liquid oat extracts prepared by extraction with alcohol, glycols, ethers, esters, mixtures, and aqueous mixtures thereof are typically unstable materials, which if not emulsified, readily separate into oil and aqueous phases which may further separate into soluble and insoluble phases. The loss of materials from solution results in hazing and the loss of functional activity. Haze is irreversible and the extract cannot be clarified by heat, dilution, addition of surfactants, or solvents or pH. Attempts to clarify the extracts using filtration resulted in the loss of functional activity. The instability of oat extracts has limited utility in cosmetic and medical applications.
Paton (19951 Cosmetics and Toiletries 110:63 describes the cosmetic use of oat extracts and provides information on cosmetic formulations. The oat extract described, OSTAR ARRIVEEN™, is produced from oats by a pearling process by which oat bran is obtained, which was then extracted with solvent. Charcoal was used in the process to clarify the preparation. The product is typically a dark brown coloured, non-homogeneous, bi-phasic extract. The utility of this product was limited by instability resulting in varying performance. The product could not be sterilised resulting in a high microbial load high due to non-kilned, non-stabilised oat bran.
Collins et al U.S. Pat. No. 5,169,660 describes the preparation of bran from cereal grains using aqueous alcohol extraction (83% w/w) and the recovery of crude by-products from waste through ion-exchange chromatography. The described process does not use pH pre-treatment or membrane filtration and so results in only recovered small quantities of by-product from waste. Utility is not described in cosmetic applications and pharmaceutical claims are not enabled.
Collins in Oats: Chemistry and technology (1986) Ed. Webster AACC St. Paul. Minn. pp 227-286 describes oat phenolic compound structure, occurrence and phytological function. Methods of extraction of these compounds and potential utility in the cosmetic and medical fields of use were not disclosed.
Onitsuka et al US 5J 16.605 describe the use of glycolic extracts of oats for the treatment and care of hair and the scalp. The extraction method described is different to the method of the present invention.
Cioca et al U.S. Pat. No. 5,552,135 describes improved sunscreen compositions including extracts from cereal plants. The primary extraction is made with chloroform or ethanol and further processed further in alcohol following evaporative concentration.
Hammonds et al PCT/US97/10724 describes fibrous sheet materials containing oat extracts to provide a soothing effect to the skin of the user. The oat extracts claimed are made by treating oats with extraction agents by methods known to those skilled in the art. Methods of preparing oat extracts are not disclosed; the described product used specific concentrations of OSTAR ARR1VEEN™ in the preferred mode.
Zimmerman U.S. Pat. No. 5,888,521 describes compositions for topical use consisting of hydroxycarboxylic acid and oat extract, and also relates to methods of enhancing the rate of skin desquamation. Methods of preparing oat extracts are not disclosed; the described product used specific concentrations of OSTAR ARRIVEEN™ in the preferred mode.
Roger et al U.S. Pat. No. 5,026,548 describes a phospholipid surfactant for use as a viscosity reducing agent in chocolate, or an emulsifier, surfactant or foam stabilizer in the food and other industries is produced by extracting oats using an alcohol such as ethanol or propanol, extracting the alcohol extract with methanol and evaporating the methanol.
Targan U.S. Pat. No. 5,468,491 describes a method for producing an aqueous oat syrup involving enzymatic digestion, cooking, filtration through on oat bed, and concentration to produce an extract composed of 80% sugars and 20% water. Utility is expressed as a flavour, colour, sweetener, and or texture enhancer. The composition is different to the present liquid oat extract.
Rouanet et al PCT/FR98/00826 describes a method for making a solid preparation of white colloidal oats, comprising the following steps: using cultivated oat seeds; stabilizing by at least one operation whereby dry vapour is injected followed by sudden cooling, preferably at about room temperature; pinning and drying; breaking and eliminating the bran; dimensional selecting of particles.
Vallet Mas et al EP 0 661 047 describes the combination of topical anti-histamines with solid oat flour to form an emulsion for the treatment of itching, reduction of inflammation and facilitation of spreading over the effected area. No reference is made to the anti-irritant potential of oat extracts.
Kovacs EP 0 282 002 describes the use of combinations of nettle (Urtica) and oat extracts as food additives or pharmaceutical preparations. The methods of preparing the oat extracts are described as, “classical methods” and no enabling details are provided.
Lawrence U.S. Pat. No. 5,573,785 describes an oat derived, skin conditioning, cosmetic component produced by dispersing in water a water-soluble fibre composed of about 4 to 6 weight percent beta glucan, about 1 to 5 weight percent fat, about 80 to 94 weight percent carbohydrates and less than 8 weight percent protein. No data relating to anti-irritant and redness reduction is provided. Furthermore, composition is radically different.
The commercial uses of ultra-filtration are known to those skilled in the art. Uses include water purification, milk processing, fruit juice, and wine clarification. However, ultra-filtration cannot be used for processing oat extracts without first stabilising the product by reducing pH. The high oil content of oats compounds this problem.
Reverse osmosis is known to those skilled in the art for the production of water from salt solutions. The use of reverse osmosis for the concentration of alcoholic extracts and solvent recovery as described in the present invention is novel.